Filter system for mobile debris collection machine

Abstract

A mobile debris collection machine which has an improved filter system includes a chassis, wheels for supporting the chassis, an operator controlled debris pickup on the chassis and a debris container on the chassis. There is a vacuum system for carrying debris from the pickup to the container, with the vacuum system including a vacuum fan located above the debris container for creating an air stream that moves dust and debris from the pickup toward the container. A filter system for removing dust and debris from the airstream includes a first filter stage formed of a rotating perforated member, a second filter stage that is located downstream of the vacuum fan and includes a mesh filter bag, and a third filter stage, located downstream from the second filter stage and including a pleated panel filter.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
     
       1. A mobile debris collection machine having an improved filter system including a chassis, a debris collection pickup on said chassis, a debris container on said chassis, a vacuum system for carrying dust and debris from said pickup to said container, 
       said vacuum system including a housing associated with said container and having a dust and debris inlet opening therein above said container, an outlet in said housing, a vacuum fan for creating an air stream that moves dust and debris into said housing and moves dust out of said housing, and a filter system for removing dust from said air stream and depositing debris into said container, said filter system including a first filter stage having a rotating filter element that separates debris from said air stream and is located upstream of said vacuum fan, a second filter stage that is located downstream of said vacuum fan, and a third filter stage downstream of said second filter stage and positioned outside of said housing.  
     
     
       2. The mobile debris collection machine of  claim 1  wherein said first filter stage includes a rotating filter element positioned adjacent to and driven by said vacuum fan. 
     
     
       3. The mobile debris collection machine of  claim 2  wherein said rotating filter element is a dish-like plate attached to said vacuum fan and located above said container. 
     
     
       4. The mobile debris collection machine of  claim 1  wherein said second filter stage is located outside of said container and consists of a mesh filter bag. 
     
     
       5. The mobile debris collection machine of  claim 4  wherein said second filter stage is located within an enclosure positioned outside of said housing. 
     
     
       6. The mobile debris collection machine of  claim 5  wherein said third filter stage is located within said enclosure. 
     
     
       7. The mobile debris collection machine of  claim 6  including a bypass between said second and third filter stages. 
     
     
       8. The mobile debris collection machine of  claim 7  wherein said bypass includes a door located at the bottom of said enclosure. 
     
     
       9. The mobile debris collection machine of  claim 1  wherein said third filter stage includes a pleated filter element. 
     
     
       10. The mobile debris collection machine of  claim 9  wherein said second filter stage includes a mesh filter bag positioned side by side with said pleated filter element. 
     
     
       11. A mobile debris collection machine having an improved filter system including a chassis, a debris pickup on said chassis, a debris container on said chassis, a vacuum system for carrying dust and debris from said pickup to said container, 
       said vacuum system including a housing associated with said container and having a dust and debris inlet opening therein, an outlet in said housing, a vacuum fan for creating an air stream that moves dust and debris into said housing and moves dust out of said housing, a filter system for removing dust from said air stream and depositing debris into said container, said filter system including a first filter stage formed of a rotating filter element driven by said vacuum fan, a second filter stage, located downstream of said vacuum fan, and a third filter stage, located downstream of said second filter stage.  
     
     
       12. The mobile debris collection machine of  claim 11  wherein the second filter stage includes a mesh filter bag, and the third filter stage includes a pleated filter element. 
     
     
       13. The mobile debris collection machine of  claim 12  wherein openings in said mesh filter bag are smaller than openings in said rotating filter element and openings in said pleated filter element are smaller than opening in said mesh filter bag. 
     
     
       14. A mobile debris collection machine having an improved filter system including a chassis, a debris collection pickup on said chassis, a debris container on said chassis, a vacuum system for carrying dust and debris from said pickup to said container, 
       said vacuum system including a housing associated with said container and having a dust and debris inlet opening therein above said container, an outlet in said housing, a vacuum fan for creating an air stream that moves dust and debris into said housing and moves dust out of said housing, a filter system for removing dust from said air stream and depositing debris into said container, said filter system including multiple filter stages downstream of said debris container allowing air to exit the machine after passing through all of the multiple filter stages during a normal operation condition, and a bypass door allowing air to exit the machine after passing through at least one but not all of the multiple filter stages during a bypass condition.  
     
     
       15. A method of collecting debris with a machine including the steps of: 
       providing a chassis, a debris container on said chassis, and a vacuum system for carrying dust and debris to said container, wherein said vacuum system comprises a vacuum fan;  
       operating the vacuum fan to create an air stream that moves dust and debris into said container and moves dust out of said container;  
       providing a filter system including multiple filter stages downstream of said debris container;  
       removing dust from said air stream and depositing debris into said container;  
       allowing air to exit the machine after passing through all of the multiple filter stages during a normal operation condition; and  
       allowing air to exit the machine though a bypass door after passing through at least one but not all of the multiple filter stages during a bypass condition.  
     
     
       16. A method of debris collection with a mobile machine, including the steps of: 
       providing a chassis, a debris container on said chassis, a debris collection pickup on said chassis, and a vacuum system for carrying dust and debris from said pickup to said container, said vacuum system including a vacuum fan;  
       operating the vacuum fan to create an air stream that moves dust and debris into said container and moves dust out of said container;  
       providing a filter system including a first filter stage having a rotatable filter element proximate to the container, and a second filter stage located downstream of said vacuum fan;  
       removing dust and debris from said air stream and depositing debris into said container; and  
       rotating the rotatable filter element to separate debris from the air stream prior to the second filter stage.